Force constant

Two 3.5 g masses are attached by a spring has a vibrational frequency of 7.00 s-1. Calculate
(a) the force constant of the spring; (b) the zero point energy; (c) the potential energy if the
maximum displacement is 0.5 cm.

2. Relevant equations
k=((2πcω)^2)μ
E=(1/2)hcw

(NOTE: The omega(w) in the formulas has a ~ over the top representing wave number which has the units 1/cm)

3. The attempt at a solution

The question gave me the vibrational frequency of 7.00/s. I don't how to put the frequency in terms of 1/cm so i can plug it into the force constant formula